The X-Ray-faint Early-Type Galaxy NGC 4697
Abstract
We analyze archival ROSAT HRI, ROSAT PSPC, and ASCA data of the X-ray-faint early-type galaxy NGC 4697. The joint ROSAT PSPC+ASCA spectrum is fitted by a two-component thermal model, a MEKAL model with kTMEKAL=0.26+0.04-0.03 keV with low metallicity and a bremsstrahlung model with kTBREM=5.2+3.0-1.6 keV. A similar model was found to fit the spectra of another faint early-type galaxy (NGC 4382) and the bulge of M31. We interpret this soft emission as a combination of emission from a soft component of low-mass X-ray binaries (LMXBs) and from a low-temperature interstellar medium, although the relative contributions of the two components could not be determined. Twelve point sources were identified within 4' of NGC 4697, of which 11 are most likely LMXBs associated with the galaxy. The soft X-ray colors of four of the LMXBs in NGC 4697 support the claim that LMXBs possess a soft spectral component. Finally, we present a simulation of what we believe the Chandra data of NGC 4697 will look like.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2000
- DOI:
- 10.1086/317196
- arXiv:
- arXiv:astro-ph/0007408
- Bibcode:
- 2000ApJ...544..293I
- Keywords:
-
- Stars: Binaries: Close;
- Galaxies: Elliptical and Lenticular;
- cD;
- Galaxies: ISM;
- X-Rays: Galaxies;
- X-Rays: ISM;
- X-Rays: Stars;
- Astrophysics
- E-Print:
- 10 pages, uses emulateapj.sty, accepted by Astrophysical Journal